Who I have the same questioned this topic

My Samsung Galaxy J7V has an up-to-date system as of 9-20-2018.  There are times people are trying to call me and nothing happens.  They do not hear my phone ring, voicemail doesn't come on, etc.  After several attempts the call may go thru, but when I answer I cannot hear them and they cannot hear me.  This happens repeatedly until I restart my phone.  After the restart the phone works.

I don't have anyone BLOCKED, AirPlane Mode is OFF, notifications are ON, Bluetooth and WiFi are ON.

Any ideas as to why this is happening?  Thanks in advance for any help.